Write-head having recessed magnetic material in gap region

ABSTRACT

As track densities increase, it becomes increasingly important, while writing in a given track, not to inadvertently write data in adjoining tracks. This problem has been overcome by limiting the width of material in the ABS plane to what it is at the write gap. The part of the lower pole that is wider than this is recessed back away from the ABS, thereby greatly reducing its magnetic influence on adjacent tracks. Four different embodiments of write heads that incorporate this notion are described together with a description of a general process for their manufacture.

FIELD OF THE INVENTION

The invention relates to the general field of magnetic write heads withparticular reference to eliminating neighboring track erasure.

BACKGROUND OF THE INVENTION

A typical write head structure for a magnetic disk system isschematically illustrated in FIG. 1. Its principal parts are lower pole12 and upper pole 11 (commonly referred to as P1 and P2, respectively.These are magnetically connected at one end and separated by a smallnon-magnetic layer 13 (the write gap) at the other end. The track widthwill be defined by the P2 width at the gap. P1 may be notched through aself aligned process, known as partial pole trim (PPT), to better definethe written transitions. Coil 14 is located in the space enclosed by P1and P2 and is the source of the magnetic field that is focused by thetwo pole pieces. All seen in the figure is a magnetic shield layer 16which is electrically isolated from the lower pole by dielectric layer15.

FIG. 2 shows a variation on the basic design seen in FIG. 1. In thiscase a secondary upper pole 21 is ‘stitched’ in between 11 (P2) and gap13. This is for ease of fabrication so that the track width definitioncan be done on relatively flatter topography. An additional feature, notpresent in the design of FIG. 1, is shallow trench 22 which is etchedinto lower pole 12. Since trench 22 has sloping sides, the depth towhich it is etched can be used to fine tune the length of lower pole 12that is part of the write gap 13. This is usually referred to as thethroat. This allows for a further concentration of the available fluxwithin the write gap. In the stitched pole design, the track width isdefining part of pole 21 as well as the back gap connection 23 which arefabricated immediately following the deposition of write gap 13.

FIG. 3 is an isometric view of part of FIG. 1 or FIG. 2 as seen whenlooking up from the magnetic track at the air bearing surface thatpasses over it (so-called ABS view). It is important to note that thesurfaces of the upper pole (11 in FIG. 1 or 21 in FIG. 2), the gap 13,and the lower pole 12, are all coplanar. One consequence of this, thestandard structure in use today, is the unintended erasure of adjacenttracks on the disk as narrower tracks and higher track densities aredeveloped. Most improvements that have been proposed, such as increasedPPT depth, smooth P1 topography, and narrower gap all come with eitherprocess challenges or reduced on track writeablity performance.

As track densities increase, the read head extracts the recordedinformation from an ever decreasing narrow track. It becomesincreasingly important not to affect the integrity of this narrow trackof data. In the structure shown in FIG. 3, P2 has magnetic materialconfined to the written track. P1. however, still includes material thatextends outside the track width (TW) defining region. This may lead tounintended writing on an adjacent track and may therefore affect thedata integrity of the system.

A routine search of the prior art was performed with the followingreferences of interest being found:

U.S. Pat. No. 6,353,511 B1 (Shi et al.) shows a process for a improvedWrite head. U.S. Pat. No. 5,878,481 (Feng et al.) shows a pole trimmingprocess for a write head. U.S. Pat. No. 5,843,521 (Ju et al.) and U.S.Pat. No. 5,802,700 (Chen et al.) are related patents. U.S. Pat. No.5,652,687 (Chen et al.) shows a planarized write head process.

SUMMARY OF THE INVENTION

It has been an object of at least one embodiment of the presentinvention to provide a magnetic write head that does not writeunintentionally onto data tracks located on either side of the trackthat is being written.

Another object of at least one embodiment of the present invention hasbeen that this be accomplished without a reduction in write fieldstrength or track density.

Still another object of at least one embodiment of the present inventionhas been to provide a process for the manufacture said write head.

A further object of at least one embodiment of the present invention hasbeen that said process not require significant modification of existingprocesses for the manufacture of write heads.

These objects have been achieved by limiting the width of material inthe ABS plane to what it is at the write gap. The part of the lower polethat is wider than this is recessed away from the ABS, thereby greatlyreducing its magnetic influence on adjacent tracks. Four differentembodiments of write heads that incorporate this notion are describedtogether with a description of a general process for their manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a basic read head design.

FIG. 2 shows the basic design of FIG. 1 modified by use of a stitchedupper pole.

FIG. 3 is the ABS view of FIGS. 1 and 2 in isometric projection.

FIG. 4 shows the structure of FIG. 1 modified according to the teachingsof the present invention.

FIG. 5 shows the structure of FIG. 2 modified according to the teachingsof the present invention.

FIG. 6 illustrates a third embodiment of the present invention.

FIG. 7 is an isometric view of a portion of a fourth embodiment.

FIGS. 8-12 illustrate successive steps in the manufacture of thestructure of the present invention.

FIG. 13 is a plan view of the structure of the present invention.

FIG. 14 is an isometric view of part of a fourth embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The key novel feature of the present invention is the restriction of thewidth of P1 to TW for a distance such that there is no P1 wider than thetrack width at the ABS. This is achieved by causing P1 beyond thisdistance to be recessed away from the ABS, thereby greatly reducing itsmagnetic influence on the adjacent tracks. Thus, the amount of P1 at theABS should exceed the amount of P1 that is recessed

1^(st) Embodiment

Referring now to FIG. 4, we show there a structure that is similar tothe one shown in FIG. 1, but modified in accordance with the teachingsof the present invention. As before, upper pole 11 and lower pole 12enclose, between them, field coil 14. The key novel feature is ledge 41of magnetic (high permeability) material that extends outwards away fromthe main body of lower pole 12. The outer edge of ledge 41 has the samewidth as, and is in alignment with, the outer edge of top pole 11 sothat write gap 13 lies between them and said widths define the trackwidth TW. As a result, most of bottom pole 12 is set back some distancefrom the ABS and so has relatively little magnetic interaction with thedisk surface. FIG. 7 is an isometric view that illustrates the spatialrelationships between top pole 11 and bottom poles 41 and 12.

For purposes of simplification, FIG. 4 has been drawn as though ledge 41is a cantilever. In actuality, a layer of insulation is present below 41to support it. Details of this support layer are provided later, in thesection where we describe the process for manufacturing this structure.

2^(nd) Embodiment

FIG. 5 shows a structure similar that seen in FIG. 2. As before, thereis a general similarity to the first embodiment illustrated in FIG. 4with the addition of stitched secondary top pole 21 and shallow trench22. The key departure is the addition to the structure of ledge 51,which analogous to ledge 41 of the first embodiment, and serves the samepurpose. FIG. 7 is an isometric view that illustrates the spatialrelationships between top pole 21 and bottom poles 51 and 12 while FIG.13 is a plan view of this structure.

3^(rd) Embodiment

This variation of the basic structure is sometimes preferred becausecertain parts, such as pole 11, are easier to manufacture. By going to asomewhat thicker inter-pole connector 23 and using a single turn forfield coil 23, top pole 11 can be flat rather than humped, as in theprevious two embodiments. The bottom pole in this case is composed oftwo layers, 62 and 12, which, in prior art versions of this variant (notshown), would extend from bottom pole 12 all the way to write gap 13.

As seen in FIG. 6, in the structure of the present invention thesecondary bottom pole is in two parts 62 and 63. Part 62 extends upwardsfrom bottom pole 12 but not all the way to write gap 13. This leavesroom for second part 63 which, in addition to extending the rest of theway up to the write gap, also extends laterally away from part 62 so asto be aligned with the ABS end of top pole 11. As a result, the lowerpart of the secondary bottom pole and all of the main bottom pole 12 areset back from the ABS, thereby reducing their magnetic interaction withthe write track.

4^(th) Embodiment

This embodiment, illustrated in FIG. 14, entails still furthermodification of the three embodiments just discussed. In all threecases, there is no recessing of the secondary lower poles, recessingbeing delayed so that portion 12 a of the primary lower pole alsoremains coplanar with the ABS. The remainder 12 b of the primary lowerpole is recessed as in the previous embodiments. This embodiment isunsuitable for extremely high track densities (greater than about125,000 tracks per inch) but for lesser densities its advantage ismanufacturability; the thickness and height of 12 a (the non-recessedpart of P1) and the depth of the partial pole trim (41, 51, 62) do notneed to be the same.

Manufacturing Process

Referring now to FIG. 8, the process of the present invention beginswith the provision of substrate 15 on which is deposited, and thenpatterned, layer 12 of a high magnetic permeability material to form theprimary lower pole. Next, as seen in FIG. 9, layer of insulatingmaterial 91 is deposited on substrate 15 as well as on primary lowerpole 12, making sure that its thickness exceeds that of 12.

The structure is then planarized until all insulating material has beenremoved from over the primary lower pole so that the remaininginsulation abuts, and extends away from, the primary pole. This isillustrated in FIG. 10. Second layer 110 of high magnetic permeabilitymaterial is next deposited and patterned to form a secondary lower polethat covers primary pole 12 and extends over insulating layer 91 on oneside so as to form ledge 112. Optionally, an additional layer 114 ofinsulation may be introduced (in the same way as just described for 91)to fill in the part above 91 that is not covered by 110. Since 110 isrelatively thin, this step may be omitted without significantconsequence.

In the case of the second embodiment (FIG. 5), shallow trench 22 isformed at this time. For all embodiments, completion of the structurenow proceeds along routine lines—field coil 14 is formed over, andinsulated from, the lower poles following which the upper magnetic pole11 is formed to overlie it. At one end the two poles are in magneticcontact with one another while at the other end they are by layer ofnon-magnetic material 13 to form the write gap whose width serves todefine the track width TW. Finally, the ABS end of the structure isplanarized as far as plane 115, thereby determining how far ledge 112extends out away from the main body of the lower pole.

1. A magnetic write head, having an air bearing surface, comprising:upper and lower magnetic poles each having a first surface, said firstsurfaces being parallel and non-opposing; extending for an amount in adirection normal to said first surfaces, one pedestal from each pole,said pedestals having second surfaces that are coplanar, parallel to,and opposed to, said first surfaces; said pedestals being separated fromone another by a non-magnetic layer whereby a write gap is defined; saidpedestals having a common width that defines a track width; eachpedestal extending away from said write gap for a distance whereby mostof said pole is set back some distance from said air bearing surface andtherefore has little magnetic interaction therewith.
 2. The write headdescribed in claim 1 wherein said track width is between about 0.05 and1 micron.
 3. The write head described in claim 1 wherein said amountthat said pedestals extend away from said poles is between about 0.1 and1 micron.
 4. A magnetic write head, comprising: on a substrate, a firstlayer of high magnetic permeability material that serves as a primarylower magnetic pole; an non-magnetic layer that abuts, and extends awayfrom, said primary pole on a first side; a second layer of high magneticpermeability material that serves as a secondary lower pole and coverssaid primary pole extending over said non-magnetic layer on said firstside as a ledge having a width; a field coil over, and insulated from,said lower poles; an upper magnetic pole that overlies said field coil,contacts said lower pole at a second side that opposes said first side,and that is separated from said ledge by a layer of non-magneticmaterial that is a write gap, said upper pole having, at the write gap,a width equal to said ledge width, whereby it defines a track width; andsaid ledge extending away from said primary lower pole by an amount. 5.The write head described in claim 4 wherein said first layer of highmagnetic permeability material is NiFe, CoNiFe, FeTaN, FeAIN, CoTaN,CoAIN, or CoFeN and has a thickness between about 0.3 and 3 microns. 6.The write head described in claim 4 wherein said non-magnetic layer issilicon oxide, aluminum oxide, tantalum oxide, Al, Rh, Ru, Cu, NiCu, orTa.
 7. The write head described in claim 4 wherein said second layer ofhigh magnetic permeability material is NiFe, CoNiFe, FeTaN, FeAIN,CoTaN, CoAIN, or CoFeN and has a thickness between about 0.2 and 2microns.
 8. The write head described in claim 4 wherein said uppermagnetic pole is NiFe, CoNiFe, FeTaN, FeAIN, CoTaN, CoAIN, or CoFeN andhas a thickness between about 0.3 and 3 microns.
 9. The write headdescribed in claim 4 wherein said width is between about 0.05 and 1microns.
 10. The write head described in claim 4 wherein said amountthat said ledge extends away from said primary lower pole is betweenabout 0.1 and 1 microns.
 11. A stitched pole magnetic write head,comprising: on a substrate, a first layer of high magnetic permeabilitymaterial that serves as a primary lower magnetic pole; an insulatinglayer that abuts, and extends away from, said primary pole on a firstside; a second layer of high magnetic permeability material that servesas a secondary lower pole and covers said primary pole, extending oversaid insulating layer on said first side as a ledge having a width and alength; a depression in said lower pole that determines the value ofsaid length; a field coil over, and insulated from, said lower pole; anupper magnetic pole that overlies said field coil and that contacts saidlower pole at a second side that opposes said first side; a fluxconcentrating pole, that contacts said upper pole and extends downwardstherefrom above said ledge and that is separated from said ledge by alayer of non-magnetic material, whereby it forms a write gap, said fluxconcentrating pole having a width, at the write gap, equal to said ledgewidth, whereby it defines a track width; and said ledge extending beyondsaid primary lower pole by an amount.
 12. The stitched pole magnetichead described in claim 11 wherein the width of said ledge is betweenabout 0.05 and 1 microns.
 13. The stitched pole magnetic head describedin claim 11 wherein the length of said ledge is between about 0.1 and 1microns.
 14. The stitched pole magnetic head described in claim 11wherein said depression has a depth that is between about 0.1 and 1Angstroms.
 15. The stitched pole magnetic head described in claim 11wherein the amount said ledge extends beyond said primary lower pole isbetween about 0.1 and 1 microns.
 16. A magnetic write head, comprising:on a substrate, a flat primary lower magnetic pole having a first lengthand first and second ends; at a separation distance over said lowermagnetic pole, a flat upper magnetic pole having a second length that isgreater then said first length whereby said upper pole has an end, thathas a width, that projects beyond said lower pole only at said firstend; said upper pole being magnetically connected to said lower pole atsaid second end; between said upper and lower poles, a field coil thatis insulated from both said poles; a secondary lower pole having firstand second parts; said first part extending upwards from said primarylower pole's first end to a first height; said second part extendinglaterally from said first part so as to be in alignment with said upperpole end; said second part also extending upwards to a second heightabove said lower pole that is greater than said first height; and saidsecond part being separated from said upper pole by a layer ofnon-magnetic material, whereby it forms a write gap, said second polehaving a width, at the write gap, equal to said upper pole width,whereby it defines a track width.
 17. The magnetic write head describedin claim 16 wherein the first length of said primary magnetic pole isbetween about 5 and 25 microns.
 18. The magnetic write head described inclaim 16 wherein the separation distance over said lower magnetic poleis between about 0.05 and 0.2 microns.
 19. The magnetic write headdescribed in claim 16 wherein the width of said upper pole end isbetween about 1.5 and 3 times said track width.
 20. The magnetic writehead described in claim 16 wherein said first height is between about0.1 and 0.5 microns.
 21. The magnetic write head described in claim 16wherein said second height is between about 0.1 and 1 microns.
 22. Amagnetic write head, comprising: on a substrate, a primary lowermagnetic pole having a first thickness, an upper surface, and first andsecond ends; part of said primary lower pole having the form of a shelfthat extends outwards away from said first end by an amount, whilesharing said upper surface, and having a thickness less than said firstthickness; a secondary lower pole, having a width, that extends upwardsfrom said shelf, to a height, and inwards from said third end by anamount; a field coil over, and insulated from, said lower poles; and anupper magnetic pole that overlies said field coil, contacts said primarylower pole near said second end, and that is separated from saidsecondary lower pole by a layer of non-magnetic material, whereby itforms a write gap, said upper pole having a width, at the write gap,equal to said secondary lower pole width, whereby it defines a trackwidth.
 23. The magnetic read head described in claim 22 Wherein thethickness of said primary lower magnetic pole is between about 0.5 and 3microns.
 24. The magnetic read head described in claim 22 wherein thethickness of said shelf is between about 0.2 and 2 microns.
 25. Themagnetic read head described in claim 22 wherein the amount that saidshelf extends outwards is between about 0.1 and 2 microns.
 26. Themagnetic read head described in claim 22 wherein the width of saidsecondary lower pole is between about 0.05 and 1 microns.
 27. Themagnetic read head described in claim 22 wherein the height that saidsecondary lower pole extends upwards from said shelf is between about0.2 and 2 microns.
 28. The magnetic read head described in claim 22wherein the amount that said secondary lower pole extends inwards fromsaid third end is between about 0.05 and 0.2 microns.
 29. A process tomanufacture a magnetic write head, comprising: on a substrate,depositing and then patterning a first layer of high magneticpermeability material to form a primary lower magnetic pole; depositinga layer of insulating material on said substrate and on said primarylower pole to a thickness greater than that of said primary lower poleto form a structure; planarizing the structure until all insulatingmaterial has been removed from over said primary lower pole, wherebysaid insulating layer abuts, and extends away from, said primary pole onone side; depositing and patterning a second layer of high magneticpermeability material to form a secondary lower pole that covers saidprimary pole and extends over said insulating layer on said one side asa ledge having a width; forming a field coil over, and insulated from,said secondary lower pole; forming an upper magnetic pole that overliessaid field coil, contacts said lower pole at a location well removedfrom said one side, and that is separated from said ledge by a layer ofnon-magnetic material, thereby forming a write gap, said upper polehaving a width, at the write gap, equal to said ledge width, therebydefining a track width; and through planarizing, removing material fromsaid ledge, said write gap, and said upper pole until said ledge extendsbeyond said primary lower pole by a final amount.
 30. The processdescribed in claim 29 further comprising: forming a stitched polebetween said write gap and said upper pole, thereby concentratingmagnetic flux from said upper pole at said write gap; and prior toforming said field coil, etching a trench in said lower pole wherebysaid shelf presents a reduced area to said upper pole.
 31. The processdescribed in claim 29 wherein said first layer of high magneticpermeability material is NiFe, CoNiFe, FeTaN, FeAIN, CoTaN, CoAIN, orCoFeN and has a thickness between about 0.3 and 3 microns.
 32. Theprocess described in claim 29 wherein said insulating layer is siliconoxide, aluminum oxide, tantalum oxide, Al, Rh, Ru, Cu, NiCu, or Ta andis deposited to a thickness between about 1 and 2.5 microns.
 33. Theprocess described in claim 29 wherein said second layer of high magneticpermeability material is NiFe, CoNiFe, FeTaN, FeAIN, CoTaN, CoAIN, orCoFeN and has a thickness between about 0.2 and 2 microns.
 34. Theprocess described in claim 29 wherein said upper magnetic pole is NiFe,CoNiFe, FeTaN, FeAIN, CoTaN, CoAIN, or CoFeN and has a thickness betweenabout 0.2 and 2 microns.
 35. The process described in claim 29 whereinsaid upper pole width at the write gap is between about 0.05 and 1microns.
 36. The process described in claim 29 wherein the final amountthat said ledge extends away from said primary lower pole is betweenabout 0.1 and 1 microns.